Bleaching of wood



' employed.

UNITED STATES PATENT OFFICE BLEACHING 0F WOOD No Drawing. ApplicationMay 11, 1937, Serial No. 142,067

5 Claims.

The present invention relates to the bleaching of wood and moreparticularly to the bleaching of wood with hydrogen peroxide and analcoholic solution of an alkali.

In accordance with the procedures of the present invention the articleof wood to be bleached is treated with a solution containing orgenerating hydrogen peroxide. To this end the peroxide solution issprayed or brushed upon the article in amounts suflicient to bleach thesame or the article dipped or immersed in the peroxide solution. Theparticular mode of applying the solution will depend upon the type ofarticle to be treated, that is, whether the same be in the form ofveneer strips or heavier shaped and formed articles, and upon the typeof wood, whether hard or soft wood and whether the same be seasoned orsap laden. Where it is desired to bleach the wood substantiallythroughout, the wood is subject to vacuum, pressure, heat or otherconventional procedure and immersed in the peroxide to obtainsubstantially complete impregnation:

The hydrogen peroxide may be commercial grades of hydrogen peroxide,such as, 100 volume peroxide, or may be 10 to 100 volume, or theoxidizing solution may contain materials generating hydrogen peroxide insolution such as the perborates, percarbonates and the like and thealkali metal peroxides and such materials are comprised by the termhydrogen peroxide.

The wood is also treated with an alcoholic solution of an alkali. Suchsolution comprises any of the water soluble alcohols capable ofdissolving an alkali, as for instance, methyl or ethyl alcohol, thequantity of alkali dissolved therein depending upon the kind of alkaliand alcohol In general the alkali will be caustic soda, although othercaustic alkalis may be employed, such as caustic potash and the like,and

alcoholic solutions of ammonia will also serve. Suitable solutions maybe obtained by dissolving alkali metals in the alcohol. The causticalkali is generally dissolved to the extent of 3-12% although saturatedsolutions may be employed. Likewise, saturated solutions of ammonia inthe alcohol are recommended although about a 4% water added to the woodand reduces the time required to eliminate the added water and reducesthe moisture content of the wood to substantially that of the untreatedwoody article.

The alcoholic alkali may be added prior to, concurrent with or subseuent to the p'fdidde treatment, provided tha the peroxide or alkali isnot lost. Thus, the woody article may be dipped or immersed in theperoxide solution and the alcoholic alkali then sprayed r br ushed uponthe so-treated portions wl rereby the peroxide is activated and thewoodbleached. Rapid evaporation of the alcohol occurs leaving a bleachedwood surface.

We claim as our invention:

1. The method of bleaching wood which comprises treating the wood with asolution containing a peroxide and an alcoholic solution of an alkaliand permitting the alcohol to evaporate from the wood whereby theconcentration of bleaching agent in the solution in the wood isincreased and bleaching facilitated.

2. The method of bleaching wood which comprises applying to the wood asolution of hydrogen peroxide and an alcoholic solution of an alkali andpermitting the alcohol to evaporate from the wood whereby theconcentration of bleaching agent in the solution in the wood isincreased and bleaching facilitated.

3. The method of bleaching wood which comprises applying to the wood asolution of hydrogen peroxide and thereafter an alcoholic solution of analkali and permitting the alcohol to evaporate from the wood whereby theconcentration of bleaching agent in the solution in the wood isincreased and bleaching facilitated.

4. The method of bleaching wood which comprises treating the wood with asolution containing a peroxide and an alcoholic solution of a' causticalkali and permitting the alcohol to evaporate from the wood whereby theconcentration of bleaching agent in the solution in the wood isincreased and bleaching facilitated.

5. The method of bleaching wood which comprises treating the wood with asolution containing hydrogen peroxide and an alcoholic solution ofammonia and permitting the alcohol to evaporate from the wood wherebythe concentration of bleaching agent in the solution in the wood isincreased and bleaching facilitated.

HANS O. KAUFFMANN. ROBERT L. MCEWEN.

